I've recently put together a quad with DJI FlameWheel 440 frame, ESCs and motors and APM 2.0
I have few problems:
1. in Stabilize mode it's extremely difficult to hold altitude: when I slightly increase the throttle to avoid crashing the copter continues to ascend and even small change causes it to descend and it bounces up and down. I tried changing the controls but they seem to have no effect so if anyone you guide me which ones to pay special attention to, that would be great. (note: in loiter mode it's much more stable).
2. the copter also seems to have problems with holding position despite solid blue GPS light. I managed to put it to stable hover in stabilize mode and then switched it to loiter mode then without touching the sticks observed what's it doing - the copter was drifting to random positions within 15-meters radius - I would expect better from GPS (note: it was open space and no wind at all).
Any help would be very much appreciated
I would also appreciate some help with these questions, especially question 1!
My quad is very difficult to fly without altitude hold on. One little "notch" on the throttle is the difference between shooting up into the air or plummeting back down. I would love a way to have finer control of the throttle.
I should mention I generally fly heavy payloads. 5000 miAh battery with a digital camera and dog tracker gps "collar". Th quad uses the 880kv motors and the 20A ESCs.
By heavy payload, what's the all up weight (kg), thanks.
Many people use the throttle curve adjustment on their Tx, so that in the mid range they are able to flatten out the "ramp" to make it less touchy. If you have not calibrated your ESC's that may help also. Make sure on your TX settings that you are using the full range of the throttle BEFORE you calibrate the ESC and do the Radio Cal in the Mission Planner.
Thank you, that was exactly what I was looking for! I don't need a lot of fine control at the high and low ends of the throttle, but in the middle around the hover zone I need very fine control. Will definitely be trying the throttle curve on my Tx. Also my ESCs are always calibrated, I can even speak their programming language of beeps and boops.
While Doing Manual ESC Calibration according to http://code.google.com/p/arducopter/wiki/AC2_ESC, step 5 says "You will hear a musical note and then 2 beeps. After the two beeps drop the throttle to full down. You will then hear a number of beeps (3 beeps for 3 cell LiPo, 4 for 4 cell, etc) and then a single longer beep indicating the end points have been set and the ESC is calibrated"
Yes, i hear a starting beep sequence, then 2 beeps, i drop the throttle, i hear a certain beep and definitely NO long beep after it. At this point i consider the ESC to be calibrated. Am i following a wrong beep sequence?
You are correct! The long beep isn't as long as you would expect it to be. But double beep, then lower the throttle, then another beep, then the motor is armed, has worked for me.
Can this be done with the settings within Mission Planner? I went through the troubleshoot and wiki and did find some onfo but it's too overwhelming for someone who just started with APM..
Where did you find info? I would LOVE to be able to throttle curve from Mission Planner. The problem with my Tx is that it has airplane mode and heli mode. Heli mode lets me use throttle curve, but only airplane mode lets me do channel mixing. So to use throttle curve, I can only have two flight modes (can't mix channels 5 and 6).
Sorry for confusing you Stephen, I meant the PIDs - not the curve - but having said that, my understanding is that changing the PIDs should have the same effect as changing the exp in the radio (?)
Some basic info can be found here: http://code.google.com/p/arducopter/wiki/AC2_Tweaks
but it didn't seem to make any difference for me :(
@ Stephen, what type of tx do you have ?
I've switched over to my Spektrum Dx7, it supports both throttle curving and channel mixing!